June 24, 2008

Detailed Image of a Viral Protein Created

by Sam Savage

U.S. scientists using electron microscopy and 3-D computer reconstruction say they have produced the most detailed image yet of a viral protein envelope.

The University of California-San Diego researchers said the image -- showing the protein envelope of an asymmetrical virus and its viral DNA at a resolution of less than 1 nanometer -- will help determine how the virus locks onto its host and infects the cells by injecting its DNA.

Professor Timothy Baker, along with chemists Jinghua Tang and Norman Olson, assembled more than 12,000 microscopic views of frozen viral particles from different angles to determine the structure of a bacteriophage called phi29.

A comparison between images of the virus with and without its DNA cargo revealed the DNA twists tightly into a doughnut shape in the neck of the virus between its head and tail, the researchers said.

This highly distorted DNA structure is unlike anything previously seen or even predicted in a virus, said Baker.

The researchers, including molecular virologist Dwight Anderson at the University of Minnesota, report their research in the journal Structure.